Background: Psychiatric patients have an increased risk of some infections like toxoplasmosis. Investigations on Toxoplasma gondii infection among psychiatric patients have been limited in Mashhad, Northeast of Iran. In this case-control study, prevalence of T. gondii was investigated by serological method.
Methods: This case-control study was performed among psychiatric patients admitted to Avicenna Hospital in Mashhad, Northeast of Iran. Three hundred and fifty inpatients and 350 controls were examined in 2012-2013 for detection of IgG and IgM antibodies against T. gondii in their blood sera by ELISA. Socio-demographic and clinical manifestations of the patients were obtained.
Results: Anti-T. gondii IgG antibodies was found in 164 (46.85%) of 350 psychiatric inpatients and 120 (34.28%) of 350 controls. Seventeen (4.85%) of psychiatric individuals and 3 (0.85%) of control group were IgM+/IgG-indicating acute form of toxoplasmosis. There were no statistically significant differences between the case and control groups. In patient group, schizophrenic patients had the highest positive rate (46.28%) and bipolar mood disorder had the second most prevalent rate (20%). Of 162 schizophrenia patients, 65 (40.1%) had latent infection which was higher than that observed in controls.
Conclusion: The prevalence of T. gondii infection among psychiatric patients suffering from schizophrenia was more in Mashhad, compared with control group.

The aim of this cross sectional case control study was to examine the serofrequency and serointensity of Toxoplasma gondii (Tg) IgG, IgM, and DNA among patients with schizophrenia. A total of 101 patients with schizophrenia and 55 healthy controls from Sungai Buloh Hospital, Selangor, Malaysia and University Malaya Medical Center (UMMC) were included in this study. The diagnosis of schizophrenia was made based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). The presence of Tg infection was examined using both indirect (ELISA) and direct (quantitative real-time PCR) detection methods by measuring Tg IgG and IgM and DNA, respectively. The serofrequency of Tg IgG antibodies (51.5%, 52/101) and DNA (32.67%, 33/101) among patients with schizophrenia was significantly higher than IgG (18.2%, 10/55) and DNA (3.64%, 2/55) of the controls (IgG, P=0.000, OD=4.8, CI=2.2-10.5; DNA, P=0.000, OD=12.9, CI=2.17-10.51). However, the Tg IgM antibody between patients with schizophrenia and controls was not significant (P>0.005). There was no significant difference (P>0.005) in both serointensity of Tg IgG and DNA between patients with schizophrenia and controls. These findings have further demonstrated the strong association between the active Tg infection and schizophrenia.

Background: Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite that causes persistent infection in humans. A substantial literature suggests that schizophrenia is associated with increased seroprevalence of T. gondii, but a possible link of the parasite with mood disorders has not been as thoroughly investigated.
Methods: We examined the association of Toxoplasma-specific immunoglobulin G results with mood disorder outcomes in 7440 respondents from the third National Health and Nutrition Survey, which is a nationally representative sample of the United States noninstitutionalized civilian population. Regression models were adjusted for numerous potential confounders, including tobacco smoking and C-reactive protein levels.
Results: No statistically significant associations were found between T. gondii seroprevalence and a history of major depression (n = 574; adjusted odds ratio [OR]:.8; 95% confidence interval [CI]:.5-1.2), severe major depression (n = 515; adjusted OR:.8; 95% CI:.6-1.2), dysthymia (n = 548; adjusted OR: 1.1; 95% CI:.7-1.8), or dysthymia with comorbid major depression (n = 242, adjusted OR: 1.2; 95% CI:.6-2.4), all p values were > .05, including analysis stratified by gender. However, there was a significant relationship between T. gondii seroprevalence and bipolar disorder type I for respondents in which both manic and major depression symptoms were reported (n = 41; adjusted OR: 2.4; 95% CI: 1.2-4.8; p < .05).
Conclusions: In a population-based sample, T. gondii seroprevalence is not elevated in unipolar mood disorders but is higher in a subset of respondents with a history of bipolar disorder type 1.

Schizophrenia and toxoplasmosis
Schizophrenia is one of the most severe and disabling psychiatric disease that affects about 1% of the adult worldwide population. Aetiology of schizophrenia is still unknown but genetic and environmental factors are suspected to play a major role in its onset. Recent epidemiologic studies indicate that infectious agents may contribute to some cases of schizophrenia. In particular, several epidemiological, behavioural and neurochemical studies suggested the existence of an association between schizophrenia and post history of primo-infection by the Toxoplasma gondii. However, they are some limitations for this hypothesis among which the lack of correlation between the geographic distribution of both diseases and of direct evidence for the presence of the parasite in schizophrenic patients. Nevertheless the identification of physiopathological mechanisms related to the parasite could provide a better comprehension to the outcome of schizophrenia. Studies on the link between toxoplasmosis and schizophrenic may provide interesting data for the diagnosis and the development of new treatments for this disorder.